Sample Preparation and Separation of Lignans by Liquid Chromatography

Lignans are important phytochemicals found mostly in the resins of coniferous trees, but are also introduced into human diets through foods such as sesame seeds and extra-virgin olive oil. They are pharmacologically interesting mainly because of their antioxidant activities, and they have also been shown to have cytotoxic and antimicrobial effects. Lignans are typically analyzed using liquid chromatography, although the complexity of the common matrices from which lignans are studied requires extensive sample preparation methodologies beforehand. While the simplest samples, such as wines and olive oils, can be analyzed without complicated procedures, most samples will require purification through liquid‒liquid extraction or silica gel column chromatography. Lignans are most often detected using mass spectrometry or ultraviolet‒visible spectrophotometry, but other methods, such as fluorescence and coulometric electrode array detectors, have also been proven useful. In this review, we will describe the typical characteristics of lignans with focus on their main pharmaceutical benefits, as well as typical sample preparation methodologies and liquid chromatographic analyses.